The NIMH Chemical Synthesis Program was established by NIMH in 1959 and has been maintained since 1991 by the Psychotherapeutic Drug Discovery and Development program in the Division of Neuroscience and Behavioral Science at NIMH. Together with other initiatives such as the NovaScreen and Natural Products Screening Projects, the Chemical Synthesis program is an important component of NIMH's efforts to promote progress in basic and applied neuroscience. The Program is similar to others supported by NCI (antitumor compounds), NICHD (contraceptives) and NIDA (drugs of abuse). The fundamental purpose of the Chemical Synthesis Program is to identify, synthesize and distribute novel, or known but unavailable, chemical compounds of interest to the research community for use in studies related to the area of mental health. Generally, compounds that are commercially available or are provided gratis by a pharmaceutical firm are excluded from this program. Occasionally, the Program will purchase a compound for one or more investigators when the quantity required would be prohibitively expensive for an individual grant budget. Such purchases are frequently requested by researchers in third-world countries, and are decided on a case-by-case basis. The Program is available to all qualified scientists involved in research related to the field of mental health, and is not restricted to NIMH grantees. The compounds provided by the Chemical Synthesis Program have a variety of uses: as pharmacological tools, as reference standards, as biochemical or neuroanatomical markers, as biological precursors for metabolic studies, for use in elucidating structure-activity relationships, for enzyme studies, as radiolabeling precursors, and for a variety of other purposes.